Lithography system, sensor and measuring method

ABSTRACT

Lithography system, sensor and method for measuring properties of a massive amount of charged particle beams of a charged particle beam system, in particular a direct write lithography system, in which
         the charged particle beams are converted into light beams by using a converter element,   using an array of light sensitive detectors such as diodes, CCD or CMOS devices, located in line with said converter element, for detecting said light beams,   electronically reading out resulting signals from said detectors after exposure thereof by said light beams,   utilizing said signals for determining values for one or more beam properties, thereby using an automated electronic calculator, and   electronically adapting the charged particle system so as to correct for out of specification range values for all or a number of said charged particle beams, each for one or more properties, based on said calculated property values.

This application is a Reissue of 11/521,705 filed on Sep. 14, 2006 whichissued as U.S. Letters Patent No. 7,868,300 on Jan. 11, 2011 and ClaimsPriority from Provisional Application 60/718,143 filed on Sep. 15, 2005.

NOTICE: More than one reissue application has been filed for the reissueof U.S. Pat. No. 7,868,300. The reissue application(s) are 13/738,947filed Jan. 10, 2013 (this application), and Ser. No. 14/469,544 filed onAug. 26, 2014.

The present patent application is a non-provisional application claimingthe priority of a provisional application of Application No. 60/718,143,filed Sep. 15, 2005.

BACKGROUND OF THE INVENTION

The present invention relates to a multi particle beam lithographysystem, a sensor therefore and a method. Such lithography systems,alternatively denoted litho system, generally operate according to amethod for transferring a pattern onto the surface of a target, therebynormally using a so called particle beam tool for generating saidmultitude of charged particle beamlets, which beams may be scanned inone or more directions by means of electronic controls. The multitude ofbeamlets, also denoted writing beams in the following is to becalibrated by means of a sensor. A method upon which such litho systemis commonly based comprises the steps of generating a plurality ofwriting beams for writing said pattern on said target surface, usually awafer or a mask. Preferably a writing beam is constituted by an electronbeam, emitted by a writing beam source, which may e.g. comprise acathode, and which may be supplemented with writing beam shaping meanssuch as an array of apertures for converting a beam emitted by saidsource into a massive plurality of significantly smaller diameter. Also,such known litho system may be provided with collimating means fordirecting a source beam or a set of generated writing beams intoparallel.

In such known method each writing beam is deflected separately atwriting said pattern on to said target surface, for interrupting saidwriting process. This is performed by means of e.g. an array ofelectrostatic deflectors and beamlet blankers through which the writingbeams are passed within the system. Especially in case of a massivelymulti writing beam system as according to the present invention, suchdeflectors are provided with so called modulation information by asignalling means. Such part of a lithography system for writing patternsonto wafers or masks, is in the following denoted a beam tool. Such beamtool and such lithography system can in more detail be known from e.g.patent publication WO2004038509 in the name of Applicant.

Further typifying the electron beam lithography under consideration,application thereof is directed to high-resolution purposes. Nowadaysapplications are capable of imaging patterns with a critical dimensionof well below 100 nm feature sizes. Multi beam in this respect inparticular relates to so-called massive multi beam system comprisinge.g. a number of writing beams in the order of 10000 and higher. In thisrespect a typical application as currently offered by Applicantcomprises 13.000 writing beams. Future developments however are focussedto litho tools comprising a number of beams in the order of 1 million,which systems are intended to utilise a principally same kind of sensor.

Such exposure lithography systems only become commercially viable whenat least the position of all of the electron beams is preciselycontrolled. Due to various circumstances such as manufacturingtolerances and thermal drift, a beam generated in the writing beam toolof a lithography system is however likely to have one or more errorswhich render it invalid for writing. Such error may be a positioningerror, with respect to a designed grid. Such erroneous feature of a beamtool, and therewith of the lithography system, severely affects thequality of the pattern to be written. Yet, the position of an e-beamnear the surface to be exposed is required to be known within a distanceof a few nanometers and should be able to be calibrated. In known lithosystems this knowledge is established by frequent calibration of thebeam position.

Apart from above mentioned specific feature, also other features ofwriting beam are desired to be known accurately and preferably atmultiple instances, and therefore swiftly, during operation of the beamtool, in particular during writing of a wafer, so as to allow an earlyadaptation of the writing process of a wafer, and to thereby increasethe number and chance of correctly written waters or fields thereof.

Known calibration methods commonly comprise at least three steps: ameasuring step wherein the position of the electron beam is measured, acalculating step wherein the measured position of the electron beam iscompared to the desired position of that beam, and a compensation stepwherein the difference between the measured position and the desiredposition is compensated for, either in the software or in the hardwareof the lithography system or said electron beam tool thereof.

Such known measuring or calibration systems hardly pose any inhibit toelectron beam lithography tools which are characterised by a relativelylow throughput, e.g. only part of a wafer is patterned within one hour,or by a relatively limited number of writing beams as compared to amassively multi beam system, For maskless systems directed at highthroughput or with a massively multi beam system as is focused on by thepresent invention, the known calibration systems form a limiting factorto the desired high capacity and high throughput, maskless lithographysystem.

With the known methods, a charged particle beam system, e.g. an electronbeam based system, needs to be calibrated a large number of times. Wherethis may be acceptable for a single beam litho system or with a numberof beams, this circumstance becomes a problem if 13000 or more beams areto be calibrated in series. In such case the time needed for calibrationwould far outweigh the time needed for actually treating a field on awafer. Therefore, so as to increase the throughput of the known lithosystem, and in accordance with an idea underlying the present invention,the calibration procedure should be speeded up significantly.

In the art, several calibration methods for electron beam lithographysystems are known. Most use marks residing in either the wafer stage orthe wafer or in both. A sensor then performs e.g. the detection or theposition of a beam. The sensor being a charged particle sensor, measuresthe amount of secondary or reflected electrons created by the marker.

One example of a method using charged particle sensors in combinationwith a plurality of charged particle beams is provided by the U.S. Pat.No. 5,929,454. It discloses a method to detect the position of aplurality of electron beams by using marks positioned on the wafer orstage. The mark is a parallel line pattern and used for severalmeasurements. All measurements are performed by detection of eithersecondary or reflected electrons from said alignment mark upon scanning.The position of the alignment mark is determined on the basis of thedisplacement amount of the electron beams and the detection result. Suchan electron detector has the advantage of rapidly determining anyprimary or secondary electrons, however is relatively bulky, i.e.measures within a range of mm, and thereby not suited for litho systemsutilising a massive multiplicity of charged particle beams, e.g. 13000beams or more. In such latter kind of litho systems a typical pitchbetween beams is in the order of tenths of mm, e.g. typically 150 μm ina present day 13.000 beam system. Apart from the above volume feature ofthe known sensor and calibrating system, the known system is alsorelatively expensive, and moreover not capable of calibrating a massiveamount of charged particle beams in qualitative and sufficiently swiftmanner.

In a massively multi-electron-beam lithography system also otherproblems arise, in that e.g. adjacent beams should not influence theaccuracy of the position detection. Also, it is not clear with the knownmethod and system how to perform both data acquisition and dataprocessing within a reasonable limit of time for all of the massiveamount of writing beams, i.e. within a period of time which is much lessthan the period required for writing a wafer. The latter problem isespecially significant because of an additional requirement, at leaststrongly desired feature common in the art, of frequent calibration ofthe entire beam tool during the process of writing a wafer, so as tomonitor and timely compensate for e.g. said earlier indicated dynamicdrift of writing beams. Such manner of proceed prevents undue loss oftreated wafers, i.e. of performed work by an expensive machine.

SUMMARY OF THE INVENTION

The present invention solves the problem posed, of swiftly detectingcharged particle beam features of a massive multiplicity of beams byconverting the charged particle beams into light beams, thereby using aconverter element such as a fluorescent screen or a doped YAG (yttriumaluminum garnet) material, subsequently detecting the light beams bymeans of an array of light sensitive detectors such as diodes, CCD orCMOS devices, alternatively denoted by using a camera, and subsequentlyelectronically reading out the signals of said camera, i.e. of the cellsor detectors thereof. In an embodiment the signals of said camera, i.e.of the cells or detectors thereof are read out in a single operation,either successively, preferably at a high clock rate. or in parallel,i.e. simultaneously. The signals are read out after a predeterminedperiod of time of exposure and are used for determining values for oneor more beam properties by means of an automated electronic calculator.The calculated property values are used for calibrating all or a numberof said writing beams. Such modification may either be performed byelectronically modifying pattern data, thereby allowing for the actualbeam properties, and/or by influencing the beams themselves. Accordingto preferred embodiment, calibration is solely performed in software bymodifying said pattern data.

Such light sensitive detectors generally have a rather poor performancein that the response of light sensitive sensors such as a CCD (chargecoupled device) is slow. It is the merit of the present inventionhowever to have conceived that despite such slow response, thesurprising composition of the sensor according to the invention,achieves a relatively very fast sensor as compared to utilising one or anumber of known electron beam detectors. In this respect advantageoususe is made from the capability of reading out a large number of lightsensitive detectors, alternatively denoted cells, in a single operation,either successively, preferably at a high clock rate, or simultaneously.In the sensor according to the invention all of the light sensitivedetectors are preferably read out simultaneously. Moreover, the presentsensor structure, in particular by the array of light detectors, enablesa very small pitch of a multiplicity of beams to be measured without thenecessity of unduly large structural measures in the region of the stagepart of a litho system.

The latter feature of measuring light signals, i.e. photons is known perse from the field of digital cameras, where also a multiplicity of lightdetectors is electronically read out at least virtually simultaneously.By utilising such a kind of array of detectors, the beam sensoraccording to the invention may as a further advantage thereat, berealised in a very cost-effective manner. The purpose of measurementsaccording to the present invention is to determine the positioning ofwriting beams and to determine if they are within specification.Measuring is performed under either one condition where a writing beamis continuous on, or where such beam is set on, on a timed basis. Bothtypes of measuring may be performed in combination for determining avalue for different beam properties as will be set out in the following.At measuring according to the invention, so-called point spreadfunctions are determined for each respective writing beam. Rise and falltimes of a beam are not measured directly, however are derived from suchfunction.

It is remarked that also the idea of converting charged particle beamsinto light beams is known per se, in this case however, from yet anothertechnological field, namely from the field of electron microscopes. Inthis field of technology, directed to accuracy rather than tospeediness, it is known per se to convert an electron beam into lightusing a converter element. Often such converter element is embodied by aso-called YAG (yttrium aluminum garnet) screen, however could e.g. alsobe a fluorescent screen. The photons subsequently realised by suchconversion are received by a so-called photomultiplier for an amplifiedelectric signal that is subsequently to be attained. Suchphoton-electric conversion is performed by a single converter cell.

In the latter respect, the present invention might also be characterisedas having solved the problem posed by the fact that a writing beam sizeis notionally smaller than the resolution of known sensors. Also atscanning over a mark the known detector is considerably larger than thepitch between two beams of the litho system currently improved: with theknown detector the signals of a plurality of writing beams wouldoverlap. As to the further problem and current solution with respect tosize of the known detector, it is to be noticed that the scanningdetector system according to the invention may, for the said massivemultiplicity of beams, typically be applied within a pitch of 150 μm(micrometer). In this respect, the diameter of a writing beam typicallyis smaller than 45 nm (nanometer). In contrast, the present inventionenables and is directed to a method, system and sensor, wherein the spotsize of a charged particle beam is smaller than the resolution of theconverter element. This is realised by utilising measured intensityvalues of a light beam for determining beam properties, in particular incombination with a knife edge, as will be exemplified in the descriptionof the figures. Such determination is performed on the basis of aplurality of signals resulting from a stepping proceed of a chargedparticle beam which is scanned in one direction at a time over a mark orblocking element.

Furthermore, the light conversion in the manner according to theinvention allows the use of relatively cheap light sensitive detectors,i.e. arrays thereof, such as CCD (charged coupled devices) and CMOS(complimentary metal-oxide semiconductors) devices. Such light detectorsconvert light into intensity counts, often electron based, and have theadvantage that they are widely available, technically well known andcost effective. They come in rather compact form, meaning that a veryhigh pixel resolution can be obtained. In other words, a massive amountof charged particle beams, after conversion into light beams, can besensed at the same time. In line with this advantage, such individuallight or pixel sensors can be read out at least virtuallysimultaneously, that is in a single operation, either successively,preferably at a high clock rate, or simultaneously. An example of thisfeature is set by reference to the application of such sensors indigital cameras.

By virtue of these above said features of at least virtuallysimultaneously reading out and conversion a charged particles intolight, a relatively slow light sensor as compared to above mentionedknown charged particle sensor, can be used to still make the calibrationof a massively multi charged particle beam tool both significantlyfaster and cheaper than at use of charged particle sensors, all withoutundue requirement of space, and all enabling a for massive multi-beamsystems required resolution. The new sensor, calibration method andlithography system enables the calibration of a massive multi chargedparticle beam tool in a highly economic manner, despite a seeminglycomplexity due to the number of structuring elements of the new sensorand due to the physical conversion method applied therein.

In a sensor according to the invention an accumulated charge orintensity at each cell is at a predetermined time read out individually.In a CCD device, a charge of a light sensitive element thereof inducedby the impingement of light thereon, is normally transported across thechip and read at one corner of an array. An analog-to-digital converterturns each pixel's value into a digital value. In CMOS devices, commonlythere are several transistors at each pixel that amplify and move suchcharge, using wiring for transporting the charge to a read out part ofthe device.

A rather favourable feature of the present invention over the knownsensors for charged particle beams tools is that rather than usingscattered or secondary electrons, the new sensor can directly measureone or more writing beams, i.e. in the sense that the sensor candirectly be located in the projection of a writing beam, i.e. in thesurface area of a wafer, which brings about significant spatialadvantages in the design of the beam tool.

A further advantage of the system according to the invention is thatdespite of the economic nature of it, rather than position only, amultiplicity of features of the beam tool is determined during a singlemeasurement thereof, thus adding up to the efficiency of both the newsensor, and the beam tool to be calibrated. Such features include beamposition, beam spot size and beam current, as well as functioning ablanking element common to such beam tools, and timing delay thereof atfunctioning.

The invention further relates to partly blocking a beam directed to thesensor by means of a blocking element provided with a knife edge,thereby enabling measurement of a maximum dimension of a spot created bysaid beam on the sensor in a favourable and effective manner. The beamis scanned, in fact stepped relative to the sensor and thereby relativeto said knife edge while optionally being switched on and off atpredetermined intervals of time, thereby creating a limited amount ofdata that can favourably be used for deducting beam properties by usingline fitting software. Such stepping can according to the invention berepeated for one or more times, preferably each time at increasedintervals of time. The beam properties are determined on the basis of aset of signals obtained while mutually shifting the beam blockingelement, i.e. mark and the charged particle beam, thereby using ablocking element included at a known position relative to the converterin said sensor.

A beam is preferably stepped over such above mentioned knife edgedblocker or mark in at least three directions, thereby enabling ellipsefitting. A mark is thereto preferably embodied hexagonal, therebyfavourably optimising sensor time by enabling stepped scanning anddetection both in back and forth direction of a beam sweep in onedirection. Such mark is according to the invention technically andeconomically favourably included at a known position relative to thesensor, in particular by structurally integrating it therewith, i.e.mounting it on top, i.e. to the surface of the sensor.

For some measurements, i.e. at least for measuring writing beam currenthowever, a beam is directed at a location on said sensor surface whereit is not intercepted by the said beam blocking mark.

Adaptation of the system on the bases of such automatically deductedbeam property values is performed by at least one of electronicallymodifying electronic data, in particular control data, for a pattern tobe imaged by said charged particle beam system, modifying line width,and electronically influencing a position modifying means of said beamsystem, for modifying the position of one or more charged particlebeams, in particular by introducing a time delay.

Especially, however not exclusively in the case of Application of a CMOSdevice, in the sensor according to the invention, a light beammodificator such as a fiber array or a lens system may be integratedbetween the converter and the receptor for optically modifying, i.e.increasing or decreasing the image of an emitted light beam, therebyoptimising the internally generated light beam for the light sensitivereceptor.

In a calibrating system according to the invention, values for the abovefeatures are derived from a multiple beam sensor by a calculating unit.Correction signals generated by this unit are according to the inventioneither used for influencing the beam tool, or for influencing an imagepattern stored in a computer means, which pattern in fact forms aninstruction basis for the beam tool.

Due to the size of the new sensor, it can be and is according to theinvention placed at multiple positions in a beam tool. In this mannercalibration frequency is increased without wasting valuable operatingtime by significant movement of the target, i.e. wafer, in particular asensor associated therewith, for correct positioning thereof relative tothe beam tool in use.

In a further elaboration of the method and lithography system accordingto the invention, the charged particle beam system, at least the beamgenerating part thereof is provided with an optical sensor. The detectorfor detecting beam properties, in particular the pattern of blockingelements thereon is utilised for optically detecting the position ofsaid system relative to an independently moveable stage for holding atarget surface and comprising said detector.

The various aspects and features described and shown in thespecification can be applied, individually, wherever possible. Theseindividual aspects, in particular the aspects and features described inthe attached dependent claims, can be made subject of divisional patentapplications.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will be elucidated on the basis of an exemplary embodimentof a maskless lithography system according to the current inventionshown in the attached drawings, in which:

FIG. 1 is a schematic representation of a calibration part of alithography system comprising a sensor according to the invention;

FIG. 2 is a schematic representation of an embodiment of a sensoraccording to the invention, for determining characteristics of a writingbeam for a lithography system;

FIG. 3 is a schematic representation of a further embodiment of a sensorfor determining characteristics of a writing beam for a lithographysystem;

FIG. 4 is a schematic top view of the sensor embodiment according toFIG. 3;

FIG. 5 is an illustration of a signal derived from the sensors accordingFIGS. 3 and 4;

FIG. 6 in a top view represents yet an alternative and currentlypreferred embodiment of a regularly shaped six-angular mark to beincluded in a sensor;

FIG. 7 provides the a signal as derived from a spot crossing a mark,e.g. as in FIG. 6, used for determining spot size and position in thedirection of relative mutual movement between beam spot and mark, i.e.sensor;

FIG. 8 schematically represents a top view of a wafer and wafer chuck,and part of the fields on said wafer, to be processed by a lithographysystem, improved by having the present sensor located at a plurality ofstrategically selected locations outside the wafer;

FIG. 9 represents a graphical relation between measurement signalaccording to the invention and a typical Gaussian distribution ofAmperes per meter (A/m) versus size X of said spot; and

FIGS. 10 and 11 schematically illustrate a so-called timed measurementaccording to the invention, showing desired positions of beam “on” and“off” relative to a knife edge in FIG. 10, and the subsequent timingsthereof for one beam as well as a time delay used thereby in FIG. 11.

DETAILED DESCRIPTION OF THE DRAWINGS

The present invention provides a design for a lithography system fittedwith an electron beam alignment sensor suitable for transferringpatterns at contemporary requirements, e.g. of 45 nm and smaller at aspeed of 10 wafers or more per hour. The invention includes a new sensorfor detecting characteristics of projected charged particle beams suchas electron beams within a litho system known per se, e.g. fromWO04/038509 in the name of Applicant or within a multi beam inspectiontool. The new sensor comprises a scintillator, here in the form of aso-called YAG (yttrium aluminum garnet) material, combined with a CCD(charge coupled device), alternatively denoted camera. The YAG screenapplied here is a Ce (Cerium) doped garnet. Features of a chargedparticle beam are derived by automated, electronic measuring andcalculating parts on the basis of a measurement of a signal generated insuch a sensor at moving a charged particle beam relative to it. In thepresent system, normally a writing beam will be moved relative to thesensor by realising a stepping movement of it within a writing beamtool, typically over a distance around the range from a few hundred nmto 2.5 μm. Stepping is in the beam tool performed by influencing anelectric field on two deflectors, or on one deflector and a wafer stage.A beam can herewith be scanned in e.g. three different directions.During such scan, a beam blocking part provided with a so-calledknife-edge is maintained at a known position in between thebeam-generating tool of the system and the said sensor. In a favourableembodiment of the new sensor, the blocking means is fixed to the surfaceof the sensor.

The known position of said blocking part is attained by at least one andpreferably a combination of all within a set of measures comprising goodmanufacturing practice for accurate positioning, calibration of thesystem, i.e. performing measurements within the machine at installing itand preferably at regular intervals that are significantly larger thanat measuring during writing operation of a wafer and, thirdly, byoptically determining the sensor and wafer position relative to the beamtool. With respect to the latter, a particular shape of the blockingpart of the sensor is favourably utilised in the present invention. Witha known, in casu optically detectable mark on a wafer, and said marks onthe sensor, the position of the wafer with respect to the sensor isknown using an optical measuring system known per se. Alter also havingdetermined the position of a number of writing beams with respect to thesensor according to the invention in a manner as will be explained inthe following, the position of the writing beams relative to the waferis known. A further measure for enhancement of accuracy at measuring,includes that said blocking part is made as small as possible and thatit is included in the sensor on a layer of low coefficient of thermalexpansion such as glass, e.g. “zero dur” glass. With the accuracyattained in accordance with the invention, and with the known positionof writing beam relative to the sensor, in a preferred embodiment of theinvention each writing beam is positioned over a single, related mark onthe sensor.

With the system, sensor and method according to the invention aframework is provided for detecting the functioning of a beam toolblanker feature known per se, any time delay thereof, as well asposition, current and spot size of all of the beams produced by saidbeam tool. These features can now, for all beams of a massivelymulti-beam tool, be detected, within a relatively short period of time,e.g. within a minute. As will be elucidated in the following, timedelay, and positioning error of a writing beam may be measured bydifferent measuring methods, with and without using a knife-edgerespectively. Time delay in this respect is the delay between an instantof instruction “on” or “off” to the beam tool and the effect thereof atwafer, in casu sensor level.

FIG. 1 illustrates a system part and method in which a sensor Saccording to the present invention is embedded. Upon impingement of acharged particle beam 4 on sensor S, in particular on converter element1 thereof, a light beam 5 is emitted by the converter 1, which isreceived by a camera 2, i.e. at least by a photon receptor 2. After apredetermined time controlled by an electronic system clock Cl, thephoton receptor is, i.e. the individual cells are read out in aconventional manner and data is provided to a calculating unit Cu in thesystem. The calculating unit determines offset from predetermined valuesof beam features such as position and magnitude, and provides correctionvalues Cor to a control means CM for controlling the charged particlebeam tool to be calibrated. This means that either or both of memorystored data for generating a pattern and the beam tool is automaticallyadapted by said control means. Thus, for measurement of properties ofcharged particle beams such as electron beams in a multi-beam chargedparticle system, in a preferred embodiment, a so-called knife edge scanwith writing beam blocking marks 6 covering the converter, in casu YAGscreen, is performed, the pattern resulting from such scan is imagedfrom said YAG screen on a camera, preferably a CCD camera.

FIGS. 2, 3 and 4 schematically depict embodiments in accordance with thepresent invention. Besides said beam current, and the X- and Y-positionof a beam, a capability of detecting the size of an individual chargedparticle beam in e.g. x and y-direction is made possible. Convertingmeans 1 are placed on top of photon-receptive means 2. A mark 6comprising a knife edge, in FIG. 2 referred to as a first exemplary mark6, is preferably ultimately closely positioned before said convertermeans 1 in the optical pathway of the charged particle beam 4. The mark6 can be and is most preferably, as here depicted positioned directly ontop of the converting means 1. However said mark 6 may, still inaccordance with the invention, alternatively be located at a knownlocation, further away from said converting means 1, for instance on aseparate carrier plate transparent for charged particles. In a preferredembodiment, the YAG screen is also included on such carrier when it isincorporated fixed on top of the sensor, thereby allowing a desiredultimate reduction of the thickness of the beam blocking material. Thereceptive means 2 is in this example composed of a plurality, i.e. a setof grid cells 3 per beam to be calibrated, in casu sixteen cells 3,arranged as a frame of square configuration conforming to preferredembodiment. Yet, in accordance with the basic principle as conceived bythe invention, such a frame can also be embodied by a single cell 3.

Though for sake of clarity not depicted in e.g. FIG. 2, in the pathwayof an electron beam in the sensor, the latter further comprises a thinlayer for blocking background light, e.g. an aluminum layer of athickness within the range of 30 to 80 nm, included between a mark 6 orcharged particle blocking layer of the sensors and the converter. Suchbackground light blocking layer enhances quality of the sensor bypreventing background light from interfering with the light generated bythe converter, i.e. with a writing beam.

The beam blocking layer or mark 6 should according to the invention bethick enough to sufficiently block an incoming charged particle beam,while on the other hand should be thin enough to minimise defocus andedge roughness effects. Thus a mark 6 is composed of a heavy metal,preferably of a tungsten alike material, in a thickness generally withinthe range of 50 to 500 nm.

The mark 6 in the embodiment according to FIGS. 3 and 4 is composed oftwo spatially separated parts 6B1 and 6B2, and shows, in the direction 7of scanning, a first perpendicularly to said direction 7 oriented knifeedge E1, and two subsequent knife edges E2 and E3, each oriented under adifferent sharp angle with said direction as taken in top view. By thepresence of at least one such sharp angle, only one direction 7 ofscanning is required for measuring spot position. This measurement isimproved without significant increase in required scanning time, byincluding two sharp edges E2 and E3, each oriented under a differentangle. A further sensor embodiment including a mark 6C, and requiringmore scanning time, however providing a relatively superior signalquality is disclosed along FIG. 6.

A potential result of the scan performed in perpendicular direction overan edge of exemplary mark 6B depicted in FIG. 4 is drawn in FIG. 5,which represents a detected number of counts CI after a number of stepst. Before reaching the left edge E1 of said exemplary mark 6, thephoton-receptive means 2 counts the number of photons in the entirebeam, i.e. a constant number of photons CI, is detected per unit oftime. When the right side of the charged particle beam 4 hits the leftedge E1 of the mark 6 at step tA while moving towards the right intodirection 7, fewer electrons will be converted thus fewer photons willbe detected by the photon-receptive means 2. By comparing the expectedstep of reaching said left edge A, the actual position of the chargedparticle beam 4 in said first direction is in accordance with theinvention determined. While moving said charged particle beam 4 furtherin said direction 7, fewer and fewer photons are detected. Eventually atstep tB, the number of detected photons reaches a minimum value. Thecharged particle beam 4 is now entirely blocked by the mark 6B. Thelength of the scan corresponding to the steps between tB and tA is ameasure for the size of the beam 4 in said first direction 7. The stepwhere the intensity is at the middle between high and low level at anedge E1-E3 is taken as the beam position. A following edge E2 that thebeam will pass while moving in the first direction 7 is not orientedperpendicular to said first direction 7. Due to the orientation of thissecond edge E2, the writing beam 4 will reach said edge E2 at adifferent step tC depending on its position in a the directionperpendicular to said first direction in the plane of the sensor, i.e.as taken in top view. Continuing the movement in the first direction 7,more and more photons are detected by the photon-receptive means 2. Inthe depicted embodiment a position measurement in multiple directions isthus enabled by scanning in a single direction. A possible disadvantageof this detector and method may however be constituted by the amount ofdata that is required to measure the writing beam properties. Thiscurrent disadvantage however is anticipated to disappear with theevolution of computing technology.

So as to allow for sufficient scans to average out so-called measuringnoise in a method and system according to the invention, a fast camerawith binning capabilities is utilised. A predetermined minimum number ofscans is performed so as to attain a desired accuracy for determiningthe beam position within the requirement. With the present type ofdetector it is not needed that there is no dead area, both a CCD and aCMOS cameras are equally feasible. Actual application of either of thetwo is based on accuracy of available camera, binning capability and,very important, readout speed and possible frames per second.

At using a knife edge scan and an appropriate mark 6, not only theposition and the current of a single writing beam is determined, butalso the spot size in two or three directions as in accordance with apreferred embodiment. By scanning over the mark 6B the measurementsignal will be as in FIG. 5, or as in FIG. 7 at applying mark 6C of FIG.6. From the rise and fall of a signal, both the position and the sigmaof the Gaussian beam are obtained. The beam current is obtained from themaximum signal. A possible and currently preferred mark 6 is shown inFIG. 6. With the knife-edge scans, all of spot position, spot size, spotcurrent, and timing delay and functioning of blanker are in accordancewith the invention may be measured as major properties of individualwriting beams.

One property that according to an elaboration of the invention may bemeasured in an advantageous way is the beam position relative to theblanking information grid. In other words, the real beam position thatcorresponds to a blanking signal. Detected displacement of the writingbeam is according to yet further work out split up in the real physicaldisplacement of the beam and the relative time delay of a blankingsignal with respect to the internal clock Cl in a lithography systemaccording to the invention, in which the charged particle beam is turnedon and off by a blanker means acting upon an electronic (blanking)signal. At calibrating a single beam, both contributions are correctedfor.

The easiest way to calibrate said position and timing error is tomeasure the total displacement in one time. In accordance with a furtheraspect of the invention, the total of displacement is measured in asingle instant. This is performed by blanking the writing beam. Awriting beam 4 is scanned over the sensor S and switched on when it isat a pre-determined lay-out position. The beam 4 is switched on for apre-defined period of time. The for measurement required number ofelectrons is obtained by performing multiple scans over the detector 6.Since in this approach of measuring, which advantageously reduces noise,the spot of a writing beam 4 on the sensor S, is obtained by blankingthe beam 4 within the beam tool producing the beam 4, both the physicaldisplacement and the time delay is measured. Advantageously in a furtherkind of measuring, the beam 4 is switched on and off for a multiplicityof times at different positions.

It may be clear that by departing from the preceding, variousembodiments within the scope of the current invention may further bedeveloped. One example of such is provided by FIG. 6, whichschematically shows the top surface of a sensor in accordance with theinvention, showing a multiplicity of equally oriented blocking elements6, here denoted 6C. The blocking elements include at least three sharpedges C1, C2, C3 mutually oriented under an angle of 120 degrees. Inthis manner according to the invention, the measured spot properties canbe fitted with an ellipse shape. Alternatively angles of 60 degreescould be used, forming a regular triangle. In this way scanning may beperformed in at least three directions as is preferred. In a furtherelaboration of the invention however, such blocking element 6C isprovided with angles larger than 90 degrees. With such a measure, inaccordance with a concept underlying the invention, the chance of aprojected focused beam entirely being intercepted by the mark isoptimised. Alternatively posed, the chance of a beam spot being scannedover an edge part of the mark, thereby disrupting the measured signal,is minimised. Secondly, with an angle larger than 90 degrees, knife-edgescans may still be performed in more than two directions, enhancing thecapability of determining spot shape and size. The most preferred markis composed as a regular six angular shape, comprising two sets of suchsharp edges C1, C2, C3. In this manner both of the earlier mentionedfeatures are integrated in the mark, while moreover the mark providesthe possibility to collect a signal both at moving back and forth.

In a further elaboration of the preferred sensor, a plurality of thepreferred hexagon shapes is included on the surface of a sensor for eachbeam to be calibrated. In this way both a chance of a rightly positionedscan as well as the quality of measurement by having multiple,independent sharp edges within one direction is increased. In a methodfor utilising such a kind of sensor, scanning is performed preferablyback and forth in multiple directions D1 to D3 as indicated in thedrawing, each direction D1 to D3 being perpendicular to one of saidsharp edges C1 to C3. All of the marks on the surface of the sensor havethe same spatial orientation. They are preferably arranged such that atscanning a charged particle beam in one particular directionperpendicular to one of the edges of a mark, the scanned beam willencounter a correspondingly oriented edge irrespective of its positionwith respect to the sensor. In other words, correspondingly orientededges of different marks join to each other, while being dislocated. Inthis manner a scanned beam will in the neighbourhood of the positionwhere it was switched on, always encounter a knife edge oriented in thesame direction, i.e. in near vicinity marks, i.e the knife edges thereofadjoin in the in the parallel direction. Such scan D1, D2 or D3 of abeam 4 may take place over a width on said target surface area of e.g.about 2.5 μm. Otherwise posed, the mutual position of sensor, i.e. themarks thereon and beam tool is such that at scanning in one directionthe chance of encountering a knife edge is one. Favourably, the knifeedges are measured a number of times the largest expected spot width,e.g. are measured by a factor within the range of 1 to 6 times saidwidth or diameter in case of an expected round spot shape. With respectto number of marks per writing beam, a ratio of a plurality of marks perwriting beam may be utilised, thus enhancing the chance of swiftlyencountering a knife edge within the scanning range at scanning acharged particle beam. However, an even more swift result is accordingto the invention attained in an embodiment where a ratio of one mark perbeam is applied, which ratio is a.o. advantageous in that the absoluteposition of a beam can easily be determined. A typical width of aknife-edge C1-C3 in the present example with only 13000 writingbeamlets, having a typical spot size of 45 nm, would be around 270 nm,in the current example raised to 300 nm.

FIG. 7, in a manner corresponding to that of FIG. 5, by bullets 8provides an exemplary set of measurement data of at least one scan overa plurality of sharp edges in one direction, e.g. a plurality of edgesC1, and a fit trace 9 mathematically deducted from said set of measuringdata. Since the present sensor for measuring a massive multiplicity ofwriting beams is devised rather slow, the measuring frequency is low ascompared to utilised at microscopy. Where in the latter case measuringis performed in the order of kHz rather than in the order of Hz as inthe present case, alternatively denoted, where a virtually continuoussignal is attained, the present measuring system departs from theunderlying insight that a limited number of measuring data, e.g. 6readings per second, may be sufficient if a fit is performed, as well asfrom the insight that a fit, rather than a virtually actual trace issufficient for the purpose of deriving the above described beam toolcharacteristics. In the latter respect, e.g. the slope of fit trace 9 isan indication of the spot size in the scanning direction. With thepresently devised sensor, detection of feature values for a massivemultiplicity of writing beams to be calibrated will in most cases besignificantly faster than at repositioning the known, relatively fastphotocell and knife edge sensor, as known from microscopy, from beam tobeam as would in the use thereof be required for a multi beam tool. Froma signal thus attained, apart from e.g. timing delay information, alsorise and fall time is deducted, and the beam current of a writing beamis derived.

It goes without saying that various other shapes than here abovementioned may be devised for realising sharp edge scans in even morethan three, i.e. in a multitude of directions. Three directions ofscanning is however considered a reasonable amount of scanning directionfor economically rather precisely determining e.g. spot size and shape.Thus, in fact measuring is performed by stepping over the sensor, ratherthan scanning. At stepping, a beam is (switched) on when it is relativeto the sensor positioned at its expected location. From the deviation ofthe derived signal with regard to the expected signal, the spot positionerror and timing error of the blanker of the beam tool is derived. Abeam is further according to the invention switched on when the spotcreated by it on the sensor is not over a part that is blocked by amark.

FIG. 8 schematically provides a top view of a wafer as included in alitho system according to the invention. In this view various fields Fhave been omitted from the drawing for sake of simplicity of drawing.The drawing illustrates the possibility, due to the strongly reducedcosts of a sensor according to the invention, to include a plurality ofsensors 11 in close vicinity of a wafer position 10 within a lithosystem according to the invention. E.g. one sensor may be located at astarting position, e.g. at the left and top side of the wafer position10 as drawn in the example of FIG. 12. Subsequent sensors are, in termsof number of fields F, distributed at regular distances over a track 13of a particle beam projector 12 over a wafer position 10. The track 13is indicated only partly by a number of arrows. The sensors are includedin the litho system close vicinity of a wafer 10, so as to minimisetravel of the beam tool. In this schematic example, sensors 11 areincluded after every 5 or 6 fields F of a wafer. After the last group offields F is treated by the beam tool, a shift is made to the initialposition, here at the left top side of the drawing, while the wafer isbeing unloaded from the system.

As to the different types of measuring enabled by the sensor andperformed in a method according to the invention, it is remarked thatfor current measurement of a writing beam, the beams will be positionedabove a YAG area of the detector and with a continuous beam-onmeasurement the current are measured. A plurality of measurements, inthe order of 10-20 is performed and of these the average current isdetermined. With the sensor according to the invention this can be donein less than 1 second for all 13000 beams. The current variation frombeam to beam is determined from the data thus generated. The requiredtime for such current measurement, with 1 nA, typically is 160 μs.However typically within 15 μs a CCD well will be filled. Thus, a numberof measurements is performed, typically within a range around 10-15 willbe performed, and of these the average current will be determined. Thiscan be done in less than 1 second for all beams. The current variationfrom beam to beam is also determined from the data. Based on the currentmeasurement the beam tool system determines if the average current ofthe valid beams is within specification. If not, either the settings ofthe source are changed until a valid measurement has been reached, orwhen that is not possible, the system determines if the current isexpected to stay constant during the forthcoming exposure or if a sourcereplacement is required. Pulse duration variation is measured byperforming a timed switching current measurement with pre-determinedon/off ratios of a projected beam.

As already indicated in the above, with respect to beam position, DC(direct current) phase noise and point spread function of the generallyGaussian distributed spot intensity, including rise and fall time, twoalternative measurements have been developed, which will in thefollowing be discussed somewhat further in detail: one with the beamcontinuously on, and one with the beam on only on timed intervals. Withthe beam continuously on, the beans position and the point spreadfunction (PSF) of the Gaussian distribution in one direction can bedetermined. With the timed scan, the scanned PSF, including rise or falltime and the shift in scanned e-beam position is measured, including DCphase noise.

For the continuous measurement a stepped deflection is performed withthe beam on. The position of the knife-edge with respect to thedeflector voltage, a measure for the beam position change with respectto its nominal position, is determined. If the exact position of theedge is now known with respect to the wafer stage position, the exactbeam position can be determined. One measurement trace represents theintegrated beam spot. Departing from a Gaussian beam profile, the tracethus represents the integral of the Gauss function. This is used to fitthe measurement result with a cumulative Gaussian. From the fitted Gaussa PSF is determined. In case it is determined that the spot is notshaped as a Gauss, a more accurate one-time determination of the spotshape is performed. The measurement results are then amongst othersfitted with the previously measured spot shape.

FIG. 9, i.e. the left hand side graph therein, provides an illustrationof the here above discussed continuous measurement and Gaussiandistribution of intensity A/m of a spot, alternatively denoted spotshape, as created by a beam 4 on a sensor S according to the invention,or on another target such as a wafer. The right hand side graph providesCCD signal read outs Sccd against deflection of a beam, measured inapplied deflection voltages Vd in the writing beam tool for two writingbeams Bm and Bn. Each measurement as reflected on the right sidecorresponds to an area under the Gauss, integrated from infinity to acertain point on the spot, which represents the position of the knifeedge. It can be thus be seen that the trace in the right side figure,which is derived from the measurement data therein, represents anintegrated Gauss. In the present example with 13000 writing beams in thebeam tool, the deflection range for determining the position of a beamis set at 300 nm, while the knife edge is placed at a nominal originposition. In this manner it is ensured that a beam, with a displacementof maximum around 100 nm, crosses the relevant knife-edge. For settingthe step size of a measurement it is departed from a minimum number ofpoints required for fitting a Gauss curve. The amount of time needed formeasurement of each point is determined by the frame read out speed,which sets the time for each single scan.

Along FIGS. 10 and 11, as an alternative to the preceding, and as apreferred method of measuring, a timed measurement is illustrated. Witha timed measurement method the number of points per single scan isreduced significantly. FIG. 10 in this respect illustrates thisso-called timed knife edge principle with figurative representation of aknife edge and the required “on” position of a couple of respectivewriting beams B1 to B3. A “positioning” of a writing beam “ON” isachieved by using a time delay per channel, which is available from theprevious exposure and which is provided within the system, preferably bythe beam tool, in particular from the control unit thereof. This timedelay is in FIG. 11 represented by the double-sided arrows 14, while theblocks show the period of time where a beam is set to “on” mode. Thelatter is performed by the blanking system of the beam tool, and impliesthe presence of a beam spot on the sensor. For a writing beammeasurement it may be assumed that the beam is not shifted drastically(less than 10 nm with respect to previous measurement), so a time delayper channel for the previous exposure can be used. The measurementresult thus is the position shift B1, S1-B1, S5 of the scanning writingbeam B1 with respect to the previous measurement, due to DC phase beamposition change. Also the PSF measured with this method includes therise or fall time. To perform this measurement and obtain at least fivedata points around the knife-edge, different scans are performed. Thewidth of the beam-on sequence is such that it only covers a singleknife-edge. The displacement of the beam-on position is obtained eitherin the data system or by adjusting the mean deflection voltage.

Apart from the preceding the same invention is in an alternativedescription defined along the following lines. In this respect it can bestated that the invention relates to a sensor for calibrating thepositions and validity of a plurality of charged particle beams withrespect to each other. Said apparatus or beam tool comprises a set ofcharged particle detectors having a known relative position with regardto each other. Said charged particle detector is provided with adetection area comprising a limited number of grid cells. Said limitednumber of grid cells equals at least four. The charged particledetectors are rigidly attached to each other. The validity of a writingbeam is determined by the control unit of the system according to theinvention by determining whether, with respect to a pre-determined setof properties to be measured by a writing beam sensor, all of thedetermined values of the set, i.e. each value of each respectiveproperty, fall within a predetermined range defined for each respectiveproperty.

The apparatus furthermore comprising a calculation unit: to determinethe difference between the design positions of said plurality of chargedparticle beams and positions of said plurality of charged particle beamsdetected by said set of charged particle detectors using said knownrelative position between said set of charged particle detectors, and tocalculate correction values to correct for said determined difference.The apparatus is also adapted for adaptation of an individual imagepattern of a single beam, based on calculations of said calculationunit. All the same the apparatus is adapted to adapt CD (criticaldistance) control in the same manner. All type of the indicatedadaptations may be implemented in the same apparatus if desired.

Said position correction means of the apparatus, also may comprise aplurality of electrostatic deflectors. Said charged particle detectormay comprise: converting means to convert a detected charged particle inat least one photon; photon-receptive means located behind saidconverting means along the optical pathway to detect said at least onephoton created by said converting means.

Said converting means may comprise a plate provided with a fluorescentlayer to perform said conversion and said fluorescent plate may comprisea YAG crystal. The photon-receptive means may comprise a limited numberof grid cells. An optical system may be positioned between saidconverting means and said photon-receptive means. Such optical system isarranged to direct the photons created at a certain location by saidconverting means towards a corresponding location in saidphoton-receptive means. The optical system is in an embodiment amagnifying optical system. The said mark is attached to said convertingmeans. The said charged particles beam tool is in particular embodied asen electron beam tool. The electron beam tool is more in particular alithography system.

Apart from the concepts and all pertaining details as described in thepreceding the invention also relates to all features as defined in thefollowing set of claims as well as to all details as may be directly andunambiguously be derived by one skilled in the art from the abovementioned figures, related to the invention. In the following set ofclaims, rather than fixating the meaning of a preceding term, anyreference numbers corresponding to structures in the figures are forreason of support at reading the claim, included solely as an exemplarymeaning of said preceding term.

The invention claimed is:
 1. A method of measuring properties of amassive amount of charged particle beams of a charged particle beamsystem in which the charged particle beams are simultaneously convertedinto light beams by using a converter element, using an array of lightsensitive detectors such as diodes, CCD or CMOS devices, located in linewith said converter element, for detecting said light beams,electronically reading out resulting signals for each beam individuallyfrom said detectors after exposure thereof by said light beams,utilizing said individual signals for determining values for one or morebeam properties, thereby using an automated electronic calculator, andelectronically adapting the charged particle system so as to correct forout of specification range values for all or a number of said chargedparticle beams individually, for one or more properties, based on saidcalculated determined property values, wherein determination of beamposition and/or beam spot size is performed on the basis of signalsresulting from a converted charged particle beam (4), thereby using ablocking element, configured to selectively partially and entirely blocka beam, included at a known position relative to the converter whileshifting the blocking element and the charged particle beam relative toeach another by one or more known shifts, wherein the charged particleblocking element (6) is applied integrated with said converter element,and located on a top thereof, and wherein said detector element isapplied light sensitive detectors are integrated with said converterelement, and located on a bottom thereof.
 2. Method according to claim1, wherein adaptation of the system is performed by at least one ofelectronically modifying electronic data for a pattern to be imaged bysaid charged particle beam system, modifying line width, andelectronically influencing a position modifying means of said beamsystem, for modifying the position of one or more charged particlebeams.
 3. Method according to claim 2, in which the system is adaptedsolely by modifying said electronic data.
 4. Method according to claim1, in which the spot size of said charged particle beams is smaller thanthe resolution of the converter element.
 5. Method according to claim 4,in which the intensity of a light beam is utilised for determining abeam property value.
 6. Method according to claim 5, in which aknife-edge is used in combination with said light intensity for derivinga value for a spot size in one direction.
 7. Method according to claim6, in which values for spot size in at least two directions is used forderiving a spot shape.
 8. Method according to claim 1, whereindetermination of beam properties is performed on the basis of aplurality of signals resulting from a stepping proceed of a chargedparticle beam being scanned in one direction at a time over saidblocking element.
 9. Method according to the claim 1, 8 in which a beamis switched off and on during such scan.
 10. Method according to claim1, wherein a switching “off” and “on” is incrementally delayed duringmultiple scans in one direction, relative to the starting point of thescan.
 11. Method according to claim 1, wherein pulse duration variationis determined using a measurement with predetermined beam on/off timing.12. Method according to claim 1, wherein the light beam resulting fromimpingement of a charged particle beam on said converter element isoptically modified for receipt by said light sensitive detector, inparticular by means of a lens system, more in particular such that saidresulting light beams are kept apart from one another, i.e. are modifiedsuch that no overlap between said resulting beams occurs.
 13. Methodaccording to claim 1, wherein a number of beam properties is derivedusing a beam detector comprising a beam blocking element, a converterelement, an electronically readable photon receptor element, an actuatorfor realising a relative movement of an electron beam and a beamblocker, and an electronic calculating unit (Cu), said properties atleast including one or more of beam position, timing delay of a possibleblanker device acting upon said particle beam, beam spot size, beamcurrent and blanking element functioning.
 14. The method according toclaim 1, wherein the charged particle beam system, at least the beamgenerating part thereof is provided with an optical sensor, and whereinthe detector for detecting beam properties is utilised for opticallydetecting the position of said system relative to an independentlymoveable stage for holding a target surface and comprising saiddetector.
 15. The method according to claim 1 for measuring propertiesof a massive amount of charged particle beams of a direct writelithography system.
 16. A sensor embodied for performing the measuringmethod in accordance with claim
 1. 17. A sensor for simultaneouslymeasuring one or more of a beam position and a beam spot size of one ormore individual particle beams in a lithography system characterized inthat wherein the sensor comprises a converter for converting a particlebeam into a light beam, as well as and a photon receptor arranged forreceiving a light beam emitted by said converter upon incidence of aparticle beam, and transforming light from said received light beam intoan electronic signal, enabling read out of said signal from the sensorby an electronic control system, in which a beam blocking element,configured to selectively partially and entirely block a beam, isprovided to the a surface of said converter, and in which the blockingelement is integrated with said converter and located on a top thereofand wherein said detector element photon receptor is applied integratedwith said converter element, and located on a bottom thereof.
 18. Thesensor according to claim 17, characterised in that for each beamlet aseparate blocking element is provided.
 19. The sensor according to claim17, in which the blocking element is provided with a sharp edge as takenperpendicularly to the surface of the converter means.
 20. The sensoraccording to claim 17, wherein the blocking element is provided with anumber of sharp edges.
 21. The sensor according claim 17, in which theblocking element is composed of a heavy material, of a thickness withina range from 50 to 500 nm.
 22. The sensor according to claim 17, whereinthe sensor includes a thin layer of light metal, between said blockingelement and said converter of a thickness within the range from 30 to 80nm.
 23. The sensor according to claim 17, wherein the sensor includes atleast one blocking element having three sharp edges mutually included ina hexagon shape.
 24. The sensor according to claim 17, in which anoptical system is included between the converter element and the lightsensitive detector.
 25. The sensor according to claim 17 for measuringproperties of a massive amount of charged particle beams of a directwrite lithography system.
 26. A lithography system for transferring apattern onto the surface of a target, using a charged particle beamtool, said tool being capable of generating a plurality of chargedparticle beams for writing said pattern on said surface, in which eitherone of the measuring method according to claim 1 and the sensor inaccordance with claim 17 is applied said system including a sensor asdefined in claim
 17. 27. A lithography system for transferring a patternonto the surface of a target, using a charged particle beam tool, saidtool being capable of generating a plurality of charged particle beamsfor writing said pattern on said surface, thereby turning off and oneach beam separately at writing said pattern onto the surface by meansof a blanker part of said system, and of at least in advance of awriting action, sensing characteristics of a writing beam using a sensorincluded in a position apart from said target surface, characterised inthat wherein the sensor is arranged in the system for determination ofbeam position and/or beam spot size, and for directly detecting all ofsaid writing beams simultaneously, the sensor thereto comprising aconverter converting each of said particle beams into a light beam, thesensor further comprising an array of light sensitive elements such asphotodiode elements, for detecting such light beams, and for generatingan electron charge upon exposure to light, which array is read out atleast virtually substantially simultaneously by a calculating unitproviding correcting value signals upon such read out to a controller ofthe particle beam tool, and/or to a controller for said pattern, formodifying electronic data representing said pattern, in which bothphysical displacement of a beam spot and time delay of a blanking partfor blanking a beam are measured, in which the sensor further comprisesa blocking element, configured to selectively partially and entirelyblock a beam, included on a top of said converter, and wherein saiddetector element is applied light sensitive elements are integrated withsaid converter element, and located on a bottom thereof.
 28. The systemaccording to claim 27, wherein adaptation of the system is performed byat least one of electronically modifying electronic data for a patternto be imaged by said charged particle beam system, modifying line width,and electronically influencing a position modifying means of said beamsystem, for modifying the position of one or more charged particlebeams.
 29. The System according to claim 27, in which the calculatingunit based on information from the sensor, provides corrective valuesfor correcting one or more of the position of a particle beam in twodirections of a plane substantially parallel to that of the target area,the intensity or current of the particle beam, the spot position and thespot size, and the sigma, of a Gaussian distribution feature of theparticle beam.
 30. The System according to claim 27, in which a particlebeam is scanned over said sensor and switched on at an instance where itis expectedly located at a predetermined position.
 31. The Systemaccording to claim 30, in which the beam is switched on for apre-determined period of time.
 32. System according to system claim 27,in which multiple scans are performed over the sensor.
 33. The Systemaccording to claim 27, in which a charged particle beam is scanned overthe sensor in three different directions.
 34. System according to claim27, in which a charged particle beam is scanned for a multiplicity ofsteps in a single direction over a sensor at different locations,shifted over at least three times an expected or determined spotdiameter of the beam.
 35. The Lithography system according to claim 27,comprising a stage for an object to be processed by a multi beam chargedparticle tool, said stage being provided with a multiplicity of sensorsaccording to claim 20, for measuring charged particle beam features,wherein each sensor of said multiplicity is implemented for measuringall charged particle beams of said tool at a time, and wherein sensorsof said multiplicity are distributed at various locations near saidobject to be processed, at mutual distances that are distributed suchthat calibration of the beam tool is enabled more than once at entirelytreating a wafer.
 36. The Lithography system according to claim 35,wherein said enabling is realised by distributing at least two sensorsat even, at least corresponding distances with respect to the trackwhich the beam tool is to follow relative to said object to beprocessed.
 37. Lithography system according to claim 35, wherein themethod according to claim 1, or the sensor according to claim 20 isapplied further comprising a sensor for simultaneously measuring one ormore of a beam position and a beam spot size of one or more individualparticle beams in the lithography system wherein the sensor includes aconverter for converting a particle beam into a light beam and a photonreceptor for receiving a light beam emitted by said converter uponincidence of a particle beam.